Transport code

Overview

The transports code in the transports/ directory is the code translating the streaming protocols available into a unified API.

Its roles are to:

• download the Manifest and parse it into an object that can be understood by the core of the rx-player

• download segments, convert them into a decodable format if needed, and report important information about them (like the duration of a segment)

• give networking metrics to allow the core to better adapt to poor networking conditions

As such, most network request needed by the player are directly performed by the transports code.

Note: the only HTTP request which might be done elsewhere would be the request for a directfile content. That request is not done explicely with a JavaScript API but implicitely by the browser (inclusion of an src attribute).

Implementation

This code is completely divided by streaming protocols used. E.g. DASH streaming is entirely defined in its own directory and the same thing is true for Smooth Streaming or MetaPlaylist contents.

When playing a DASH content only the DASH-related code will be called. When switching to a Smooth Streaming content, only the Smooth Streaming code will be used instead.

To allow this logic, any streaming protocol exposed in transports exposes the same interface and abstracts the difference to the rest of the code. For the core of the rx-player, we do not have any difference between playing any of the streaming protocols available.

This also means that the code relative to a specific streaming technology is within the transports directory. This allows to greatly simplify code maintenance and evolutivity. For example, managing a new streaming protocol would mainly just need us to add some code there (you might also need to add parsers in the parsers directory). Same thing for adding a new feature to e.g. DASH or Smooth.

Each streaming protocol implementation present in the transports code exports a single transport function.

The object returned by that function is often referenced as the transport pipelines. It is documented here.

MetaPlaylist implementation

A MetaPlaylist is a specific case, as it wraps other streaming protocols.

More documentation about it can be found in the corresponding API documentation.

Architecture information on it can also be found here.